Spacer bar for concrete reinforcing irons



Arifl 1968 M. SALM SPACER BAR FOR CONCRETE REINFORCING IRONS Filed Sept. 5, 1964 United States Patent @fiice 3,376,686 Patented Apr. 9, 1968 3,376,686 SPACER BAR FOR CONCRETE REINFORCING IRONS Mathias Salm, Schatfhanserstrasse 113, Winterthur, Switzerland Filed Sept. 3, 1964, Ser. No. 394,138 Claims priority, application Switzerland, Sept. 4, 1963, 10,932/ 63 10 Claims. (Cl. 52-687) This invention pertains generally to improvements in or relating to the supporting of reinforcing bars and rods in the manufacture of a concrete structure, and concerns in particular a supporting device for spacing the reinforcement a proper distance from the wall of a mould in which the product is formed, to properly space the reinforcement rods from the mould and hold the rods in an intended correct relative position relative to each other.

In particular this invention relates to a reinforcing iron spacer of the type constituting a spacer bar, primarly intended to be used as reinforcing rod support in horizontal beams and floor slabs. The main object of the present invention is to produce a simple an inexpensive spacer bar so constructed that it safely keeps the reinforcing rods at the desired distance from the wall of the mould, and this even if the reinforcing rods are exposed to excessive forces, for instance treaded upon, when preparing the reinforcement before pouring the concrete.

A further object of the invention is to produce a spacer bar, which, for a given distance between reinforcing rods and mould wall, may be used for different desired individual distances between a plurality of mutually parallel reinforcing rods supported thereby and corresponding to whole multiples of a modulus distance used in practice as unit for conventional distances between such parallel reinforcing rods.

With these and other objects in view the invention relates to a spacer for concrete-reinforcing rods, in particular a spacer bar to be used for defining the relative ositions of a plurality of parallel concrete reinforcing rods, as the case may be having similar or different diameters, at distances from each other essentially chosen at will and at a distance from a mould defined by the dimension of the spacer, said spacer being, according to the invention, characterized by the fact that it consists of an elongated spacer bar having an external surface, the radial distance of which from a centre line of the bar in all directions from said centre line varying periodically in the longitudinal direction of the bar between a smallest and a largest value, each bar surface located between successive bar surface portions having the largest radial distance from said centre line and facing radially in the same direction from said centre line constituting a reinforcing rod support surface between said successive bar portions, the sum of said smallest radius and said largest radius constituting the intended distance between a mould wall and a reinforcing rod supported by the spacer.

A spacer of the type defined may easily be manufactured in continuous strands from plastic material with an extrusion apparatus in practically unlimited length and winded on drums to be brought to a building site to be used in lengths, chosen at will by cutting the strand to pieces suitable for the purpose in each individual case.

In one embodiment of the invention as defined, the external surface of the spacer bar is defined by one or more thread-shaped port-ions, in the latter case interposed between each other in the longitudinal direction of the bar, coaxial with and surrounding a cylindrical core portion of the bar, the radius of said core portion being defined by the smallest value of the radial distance of the bar surface. Due to the fact that usually standard distances between mutually parallel reinforcing rods are used, the pitch of thread-shaped portions is preferably chosen equal to a modulus distance used in practice as unit for usual distances between parallel reinforcing rods or equal to a submultiple thereof, or, if more than one thread-shaped portion are interposed between each other in the longitudinal direction of the bar, a multiple of such modulus distance or sub-multiple thereof.

In an other embodiment of the invention the bar is rotationally symmetric, the parts of the bar having the largest radial extension thus constituting annular portions extending radially from the bar core, the surface between the parts having the largest diameter being in the shape of grooves surrounding the bar, each in a plane perpendicular to the longitudinal axis thereof.

The spacer bar may, in particular in order to save material and weight, have a hollow centre part, leaving so much material externally thereof that a desired strength of the spacer is still obtained.

When using a spacer according to the invention as transported to a building site, wound on drums, the spacer is unwound from the drum and cut to a desired length, this length in practice corresponding to the breadth of the mould in a direction perpendicular to the direction of the reinforcing rods, Whereafter the piece of spacer thus obtained may, without particular care, be placed on the mould surface. Due to the shape of the spacer bar, which, as seen from an end thereof, has the same radial extension in all directions from its centre line, there is no need to pay any attention to an up or down of the spacer.

The following dimensioning of a spacer bar according to the invention may be mentioned by way of example:

For an intended distance between a reinforcing rod and the wall of a mould of for instance inch and a distance between parallel reinforcing rods of for instance 6 inches, being a multiple of a distance modulus of 2 inches commonly used in practice, the external diameter of a spacer bar may be chosen /8 inch and the core diameter thereof inch, the distance between the larger radius portions of the bar, as seen a section through the bar axis, being 1 or 2 inches, corresponding to the modulus length or a sub-multiple thereof. If the larger radius portions of the bar are constituted by one or more threadshaped portions, the pitch of the thread should then be 1 or 2 inches, respecively. Reinforcing rods arranged in each sixth or twelvth, respectively, depression obtain the desired modulus multiple distance from each other and the intended distance from the mould.

The invention is further illustrated by the following description of embodiments thereof illustrated in the accompanying drawings, in which:

FIG. 1 illustrates a portion of a spacer bar as cut out from a continuous strand and as seen perpendicularly to the longitudinal direction thereof, in a first embodiment according to the invention,

FIG. 2 a corresponding view of a further embodiment according to the invention, having radially extending parts formed by'two interposed helical portions, and

FIG. 3 is a corresponding View of an embodiment, in which the radially extending parts are constitutedby annular portions of the spacer bar.

The reinforcing rod spacer bar according to the invention as illustrated FIG. 1 constitutes a screw-shaped body having a helical surface 1, the pitch h of which is so designed, that a whole multiple thereof corresponds to the smallest distance between mutually parallel reinforcing rods used in practice, or to a standard modulus for distances between such reinforcing rods, for instance 2 inches. correspondingly the pitch of the screw surface may be A, /2 or 1 inch. The portion of the bar restricted by the helical surface 1 surrounds a core portion 2 of the spacer. The sum of largest radius R of the helical surface 1 and radius r of the core portion 2, being also the smallest radius of the helical surface, equals the desired distance between a reinforcing rod A supported by the spacer bar and the wall S of a mould. For concrete structures in which said distance shall be /3 inch, by way of example, radius R may be chosen inch and radius r inch, the reinforcing rods arranged in the spacers between two successive windings of the helical portion of the spacer bar being then held in the desired distance inch from the mould wall.

In the embodiment as illustrated in FIG. 1, in which the larger diameter parts of the spacer constitute one helical surface only, the forces exerted on the spacer by the reinforcing rods and, as the case may be, by persons treading on the reinforcement, or other excessive load, will always act upon the spacer straight above a portion of the spacer bar in contact with the mould, the spacer thus safely holding the reinforcing iron on the desired distance from the mould also for heavy loads.

It is furthermore possible, by giving the spacer bar a shape, in which the largest radius of the bar and/or the radius of the core portion thereof is successively varying in the longitudinal direction of the bar, to arrange for a successive variation in the longitudinal direction of the spacer bar of distances between reinforcing irons and the mould.

In order to obtain an exact centration of the reinforcing irons in the spacers between the screw windings, the generatrixes 4 of the helical surface 1 is represented by a conical section or similar curve. In the embodiment illustrated in FIG. 1 this surface merges, at outermost parts of the spacer into an essentially cylindrical helical surface portion, although it may be understood that the outermost surface portion may also be rounded as illustrated in the embodiment according to FIG. 2, further described below.

The embodiment according to FIG. 2 differs from the embodiment illustrated in FIG. 1 essentially in that two axially interposed helical surfaces 5 and 6 are present, the distance between said two helical surfaces corresponding to half the pitch h of one helix.

FIG. 3 illustrates an embodiment in which successive enlargements in the longitudinal direction of a spacer bar are constituted by bar portions 8 extending radially from core portion 2 and together forming annular grooves, which constitute support surfaces for reinforcing rods, and each constituting spacing means to keep the spacer at a distance from a mould wall at parts thereof intermediate the contact points or areas between spacer and mould wall.

I claim:

1. A spacer for use in supporting concrete reinforcing rods in a mould in the manufacture of a formed concrete body, said spacer consisting of an elongated spacer bar having an external surface, the radial distance of which from a centre line of the bar in all directions from said centre line varying periodically in the longitudinal direction of the bar between a smallest and a largest value, each bar surface located between successive bar surface portions having the largest radial distance from said centre line and facing radially in the same direction from said centre line being smoothly and continuously curved and constituting a concave reinforcing rod support surface between said successive bar surface portions, the sum of said smallest radius and said largest radius constituting the intended distance between a mould wall and a reinforcing rod supported by the spacer.

2. A spacer according to claim 1 in which the portions of the bar having the largest radial distance from said centre line constitute annular portions extending radially from and surrounding a cylindrical core portion of the bar, the surface between the portions having the largest diameter forming grooves surrounding the bar, each in a plane perpendicular to the longitudinal axis of the bar.

3. A spacer according to claim 1 having a hollow centre part.

4. A spacer according to claim 1 in which the largest radius of the bar is successively varying in the longitudinal direction of the bar.

5. A spacer according to claim 1 in which the smallest radius of the bar, defining a core portion of the bar, is successively varying in the longitudinal direction of the bar.

6. A spacer according to claim ,1 in which generatrixes,

of surfaces between portions of the bar having the largest diameter constitutes a conical section.

7. A spacer as claimed in claim 1 wherein said portions with the largest radial distance are arranged on the bar so that they are in diametric opposition with portions of minimum radial distance whereby reinforcing rods can be received on said rod support surfaces and be directly supported therebeneath by corresponding portions of largest radial distance.

8. A spacer as claimed in claim 1 wherein said bar is constituted of plastic material.

9. A spacer according to claim 1, wherein the spacer bar comprises at least one helical portion co-axial with and surrounding a cylindrical core portion of the bar and extending continuously in successive windings along the bar, the surface of the bar between any two successive points on the helical portion along the same longitudinal line being said smoothly and continuously curved rod support surface, the latter being tangent to said core portion whereby the radius of said core portion is defined by the smallest radial distance of the bar surface.

10. A spacer according to claim 2 in which the external surface of the spacer bar is defined by two helical portions, said two helical portions being interposed between each other in the longitudinal direction of the bar.

References Cited UNITED STATES PATENTS 456,646 7/1891 Clark 52734 830,583 9/1906 Luten 52-736 3,252,263 5/1966 Korf' 53-685 FOREIGN PATENTS 1,109,237 9/1955 France.

295,923 7/1951 Switzerland.

HENRY C. SUTHERLAND, Primary Examiner.

JAMES L. RIDGILL, Assistant Examiner. 

1. A SPACER FOR USE IN SUPPORTING CONCRETE REINFORCING RODS IN A MOULD IN THE MANUFACTURE OF A FORMED CONCRETE BODY, SAID SPACER CONSISTING OF AN ELONGATED SPACER BAR HAVING AN EXTERNAL SURFACE, THE RADIAL DISTANCE OF WHICH FROM A CENTRE LINE OF THE BAR IN ALL DIRECTIONS FROM SAID CENTRE LINE VARYING PERIODICALLY IN THE LONGITUDINAL DIRECTION OF THE BAR BETWEEN A SMALLEST AND A LARGEST VALUE, EACH BAR SURFACE LOCATED BETWEEN SUCCESSIVE BAR SURFACE PORTIONS HAVING THE LARGEST RADIAL DISTANCE FROM SAID CENTRE LINE AND FACING RADIALLY IN THE SAME DIRECTION FROM SAID CENTRE LINE BEING SMOOTHLY AND CONTINUOUSLY CURVED AND CONSTITUTING A CONCAVE REINFORCING ROD SUPPORT SURFACE BETWEEN SAID SUCCESSIVE BAR SURFACE PORTIONS, THE SUM OF SAID SMALLEST RADIUS AND SAID LARGEST RADIUS CONSTITUTING THE INTENDED DISTANCE BETWEEN A MOULD WALL AND A REINFORCING ROD SUPPORTED BY THE SPACER. 